Heavy Snow in Oregon, December 12 to 14, 2008

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
945 AM PST FRI DEC 12 2008

UPDATED AVIATION AND SHORT TERM DISCUSSION

.SHORT TERM...UPDATE...STRONG STORM SYSTEM STILL ON TRACK TO MOVE
INTO THE PACNW TODAY. PRECIP HAS BEGUN TO REACH THE CREST OF THE
CENTRAL WASHINGTON CASCADES AND SHOULD GRADUALLY PUSH EAST THROUGH
THIS AFTERNOON. HEAVY SNOW IS EXPECTED OVER THE NEXT 24 TO 48 HOURS
ALONG THE WASHINGTON CASCADE EAST SLOPES AND OVER THE BLUE
MOUNTAINS. CURRENT WINTER STORM WARNINGS FOR THESE AREAS WILL
CONTINUE AS THEY ARE. SNOW POTENTIAL FOR OTHER AREAS WILL INCREASE
LATER TONIGHT AND ON SATURDAY AND WILL ADDRESS ADDITIONAL ADVISORIES
AND WARNINGS WITH THE AFTERNOON PACKAGE. WINDS WILL BE STRONG LATE
THIS AFTERNOON THROUGH THE OVERNIGHT PERIOD DUE TO THE STRENGTH OF
THIS STORM. WINDS ALOFT WILL GENERALLY BE PARALLEL TO THE SURFACE
PRESSURE GRADIENTS THUS EXPECT WINDS TO MAINLY BE IN THE ADVISORY
RANGE ACROSS THE COLUMBIA BASIN AND CENTRAL OREGON. THERE COULD BE A
BRIEF...LOCALIZED ONE TO TWO HOUR PERIOD OF HIGH WINDS AS THE FRONT
MOVES THROUGH THIS EVENING. AT THIS TIME CONFIDENCE IS ONLY HIGH
ENOUGH THAT THESE HIGH WINDS WILL SURFACE AND BE WIDESPREAD IN
PORTIONS OF NORTH CENTRAL OREGON AND ALONG THE OREGON BLUE MOUNTAIN
FOOTHILLS. THUS WILL ISSUE WARNINGS FOR THESE TWO ZONES AND STICK
WITH ADVISORIES ELSEWHERE. WINDS IN THE WARNED ZONES MAY DECREASE TO
ADVISORY LEVELS BY MIDNIGHT...BUT FOR SIMPLICITY WILL KEEP THE
WARNED PERIOD LONGER. 90

.LONG TERM...PREVIOUS DISCUSSION...AN UPPER LEVEL LOW WILL MOVE
SLOWLY SOUTH ALONG THE OREGON COAST ON SUNDAY THUS IMPOSING AN
EASTERLY FLOW AT 5000 FT MSL ALONG THE EAST FACING SLOPES OF THE
CASCADES FOR SNOW LIKELY IN CENTRAL OREGON THROUGH SUNDAY NIGHT.
MONDAY MODELS INDICATE THAT THE LOW WILL BE INLAND OR OFFSHORE OF
THE OREGON COAST THUS KEEPING A CHANCE OF SNOW IN THE OREGON PORTION
OF THE FORECAST AREA. FROM TUESDAY THROUGH THURSDAY THE
AFOREMENTIONED UPPER LEVEL LOW TRANSFORMS INTO A STRONG UPPER LEVEL
TROUGH THAT MOVES SOUTH AND REMAINS OVER THE SOUTHWESTERN UNITED
STATES THUS KEEPING A NORTHERLY FLOW ALOFT OVER THE PACIFIC
NORTHWEST WHICH RESULTS IN A CONTINUED INFLUX OF RELATIVELY DRY
ARCTIC AIR INTO THE REGION...THUS KEEPING TEMPERATURES BELOW NORMAL
THROUGH THURSDAY. DAYTIME HIGH TEMPERATURES WILL RANGE FROM 10 TO 20
DEGREES BELOW NORMAL OVER THIS PERIOD WITH THE COLDEST DAY OCCURRING
ON MONDAY. WEAK UPPER LEVEL DISTURBANCES IN THE NORTHERLY FLOW ALOFT
MAY PRODUCE A SLIGHT CHANCE OR A CHANCE OF SNOW SHOWERS OVER THE
MOUNTAINS ON TUESDAY...WEDNESDAY NIGHT AND THURSDAY.

&&

.AVIATION...STORM SYSTEM IS ABOUT TO ENTER THE PACIFIC NORTHWEST.
MVFR/IFR CONDITIONS IN LOW CEILINGS/VSBY DUE TO FOG FOR TAF SITES
KPDT...KPSC...KYKM...KALW WILL PERSIST UNTIL A STRONG COLD FRONT
PASSES ACROSS THE AREA THIS AFTERNOON AFTER 20Z. THEN ALL TAF SITES
WILL EXPERIENCE AT SOME TIME OR ANOTHER MVFR/IFR CONDITIONS IN -RA
WITH WEST WIND GUSTS BETWEEN 40 KTS TO 50 KTS. AFTER 05Z WIND GUSTS
TO 30 KTS WILL PERSIST WITH MVFR/IFR CONDITIONS LIKELY IN LOWERING
CEILINGS/VSBY IN -SN THROUGH TOMORROW MORNING.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  46  31  36  18 /  70  70  60  50
ALW  45  32  35  18 /  60  80  70  50
PSC  42  32  37  18 /  60  50  50  50
YKM  40  26  38  16 /  60  40  40  50
HRI  45  31  40  19 /  60  60  50  50
ELN  40  28  34  15 /  80  60  60  50
RDM  48  20  37  18 /  70  60  60  40
LGD  42  31  35  20 /  40  80  80  50
GCD  45  28  35  21 /  50  80  80  50
DLS  45  35  42  24 /  60  50  50  50

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...WIND ADVISORY FROM 3 PM THIS AFTERNOON TO 10 AM PST SATURDAY FOR
     ORZ044-504.

     HIGH WIND WARNING FROM 3 PM THIS AFTERNOON TO 10 AM PST SATURDAY
     FOR ORZ042-501.

     WINTER WEATHER ADVISORY UNTIL 12 PM PST SATURDAY FOR ORZ043.

     WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO 10 AM PST
     SUNDAY FOR ORZ502-503.

     WIND ADVISORY FROM 3 PM THIS AFTERNOON TO 10 PM PST THIS EVENING
     FOR ORZ043.

WA...WINTER STORM WARNING UNTIL 12 PM PST SATURDAY FOR WAZ501-502.

     WIND ADVISORY FROM 3 PM THIS AFTERNOON TO 10 AM PST SATURDAY FOR
     WAZ028-029-502.

     WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO 10 AM PST
     SUNDAY FOR WAZ030.

&&

TI:RRY
FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT...
WWW.WEATHER.GOV/PENDLETON
90/99/97

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
1042 AM PST FRI DEC 12 2008

UPDATED FOR HIGH WIND WARNING

ORZ041>044-049-050-501>506-WAZ024-026>030-501-502-131315-
EASTERN COLUMBIA RIVER GORGE OF OREGON-NORTH CENTRAL OREGON-
CENTRAL OREGON-LOWER COLUMBIA BASIN OF OREGON-GRANDE RONDE VALLEY-
WALLOWA COUNTY-FOOTHILLS OF THE BLUE MOUNTAINS OF OREGON-
NORTHERN BLUE MOUNTAINS OF OREGON-
SOUTHERN BLUE MOUNTAINS OF OREGON-
NORTHERN WHEELER AND SOUTHERN GILLIAM COUNTIES-JOHN DAY BASIN-
OCHOCO-JOHN DAY HIGHLANDS-
EASTERN COLUMBIA RIVER GORGE OF WASHINGTON-KITTITAS VALLEY-
YAKIMA VALLEY-LOWER COLUMBIA BASIN OF WASHINGTON-
FOOTHILLS OF THE BLUE MOUNTAINS OF WASHINGTON-
NORTHWEST BLUE MOUNTAINS-
EAST SLOPES OF THE CENTRAL CASCADES OF WASHINGTON-
EAST SLOPES OF THE SOUTHERN CASCADES OF WASHINGTON-
1042 AM PST FRI DEC 12 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL AND NORTHEAST OREGON
AS WELL AS SOUTH CENTRAL AND SOUTHEAST WASHINGTON.

.DAY ONE...TODAY AND TONIGHT

SNOW
     EAST SLOPES OF THE CENTRAL CASCADES OF WASHINGTON, EAST SLOPES
     OF THE SOUTHERN CASCADES OF WASHINGTON, KITTITAS VALLEY,
     YAKIMA VALLEY, NORTHWEST BLUE MOUNTAINS, CENTRAL OREGON,
     GRANDE RONDE VALLEY, WALLOWA COUNTY, NORTHERN BLUE MOUNTAINS
     OF OREGON, SOUTHERN BLUE MOUNTAINS OF OREGON

STRONG WIND
     EASTERN COLUMBIA RIVER GORGE OF WASHINGTON, LOWER COLUMBIA
     BASIN OF WASHINGTON, FOOTHILLS OF THE BLUE MOUNTAINS OF
     WASHINGTON, EASTERN COLUMBIA RIVER GORGE OF OREGON, NORTH
     CENTRAL OREGON, LOWER COLUMBIA BASIN OF OREGON, FOOTHILLS OF
     THE BLUE MOUNTAINS OF OREGON, NORTHERN WHEELER AND SOUTHERN
     GILLIAM COUNTIES, JOHN DAY BASIN, OCHOCO-JOHN DAY HIGHLANDS

A STRONG COLD FRONT WILL MOVE THROUGH THIS AFTERNOON AND
OVERNIGHT...BRINGING SIGNIFICANT WINTER WEATHER TO THE REGION. HEAVY
SNOWFALL WILL BEGIN NEAR THE CASCADES THIS AFTERNOON...FOLLOWED BY
THE BLUE MOUNTAINS LATER IN THE AFTERNOON. A WINTER STORM WARNING
FOR HEAVY SNOW HAS BEEN ISSUED FOR THE EAST SLOPES OF THE WASHINGTON
CASCADES AND THE BLUE MOUNTAINS. A WINTER WEATHER ADVISORY FOR SNOW
HAS BEEN ISSUED FOR CENTRAL OREGON ABOVE 3500 FEET. SEE NWS PRODUCT
PDXWSWPDT FOR DETAILS. ADDITIONALLY...STRONG WINDS WILL BE LIKELY
ACROSS MOST OF THE AREA AND A WIND ADVISORY AND HIGH WIND WARNING
HAS BEEN ISSUED. SEE NWS PRODUCT PDXNPWPDT FOR DETAILS.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

SNOW SATURDAY
     EAST SLOPES OF THE CENTRAL CASCADES OF WASHINGTON, EAST SLOPES
     OF THE SOUTHERN CASCADES OF WASHINGTON, EASTERN COLUMBIA RIVER
     GORGE OF WASHINGTON, KITTITAS VALLEY, YAKIMA VALLEY, LOWER
     COLUMBIA BASIN OF WASHINGTON, FOOTHILLS OF THE BLUE MOUNTAINS
     OF WASHINGTON, NORTHWEST BLUE MOUNTAINS, EASTERN COLUMBIA
     RIVER GORGE OF OREGON, NORTH CENTRAL OREGON, CENTRAL OREGON,
     LOWER COLUMBIA BASIN OF OREGON, GRANDE RONDE VALLEY, WALLOWA
     COUNTY, FOOTHILLS OF THE BLUE MOUNTAINS OF OREGON, NORTHERN
     BLUE MOUNTAINS OF OREGON, SOUTHERN BLUE MOUNTAINS OF OREGON,
     NORTHERN WHEELER AND SOUTHERN GILLIAM COUNTIES, JOHN DAY
     BASIN, OCHOCO-JOHN DAY HIGHLANDS

EXTREME COLD SUNDAY THROUGH THURSDAY
     EAST SLOPES OF THE CENTRAL CASCADES OF WASHINGTON, EAST SLOPES
     OF THE SOUTHERN CASCADES OF WASHINGTON, EASTERN COLUMBIA RIVER
     GORGE OF WASHINGTON, KITTITAS VALLEY, YAKIMA VALLEY, LOWER
     COLUMBIA BASIN OF WASHINGTON, FOOTHILLS OF THE BLUE MOUNTAINS
     OF WASHINGTON, NORTHWEST BLUE MOUNTAINS, EASTERN COLUMBIA
     RIVER GORGE OF OREGON, NORTH CENTRAL OREGON, CENTRAL OREGON,
     LOWER COLUMBIA BASIN OF OREGON, GRANDE RONDE VALLEY, WALLOWA
     COUNTY, FOOTHILLS OF THE BLUE MOUNTAINS OF OREGON, NORTHERN
     BLUE MOUNTAINS OF OREGON, SOUTHERN BLUE MOUNTAINS OF OREGON,
     NORTHERN WHEELER AND SOUTHERN GILLIAM COUNTIES, JOHN DAY
     BASIN, OCHOCO-JOHN DAY HIGHLANDS

ACCUMULATIONS OF SNOW WILL BE POSSIBLE AT ALL ELEVATIONS ON SATURDAY
AND SUNDAY...ALTHOUGH THE HEAVIEST ACCUMULATIONS WILL BE OVER THE
CENTRAL AND EASTERN OREGON MOUNTAINS. VERY COLD TEMPERATURES ARE
FORECAST FOR SUNDAY THROUGH THURSDAY...AND GUSTY WINDS WILL RESULT
IN LOW WIND CHILLS EARLY NEXT WEEK.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED.

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

GRAPHICAL FORECASTS OF WEATHER HAZARDS OUT TO SEVEN DAYS
ARE DISPLAYED ON THE WORLD WIDE WEB AT:

WWW.WRH.NOAA.GOV/PDT/CURRENTHAZARDS/HWO.HTML

ALL LETTERS IN THE ABOVE URL ARE LOWER CASE...EXCEPT THE H IN
CURRENTHAZARDS.